Photographic material



United States Patent 3,148,987 PHQTOGRAPHIC MATERIAL Jozef FransWillems, Wilrijk-Antwerp, Belgium, assignor to Gevaert Photo-ProductenN.V., Mortsel, Belgium, a Belgian company No Drawing. Filed Oct. 2,1961, Ser. No. 142,016

' 3 Claims. (Cl. 96-10?) The present invention relates to fog inhibitingcompounds and stabilizers for light-sensitive photographic emulsions andalso to the use of these compounds in lightsensitive photographicmaterial.

It is known that light-sensitive photographic emulsions, on storage in aplace of a high temperature and a high relative humidity or whereinthese materials come into contact with some substances such as hydrogensulphide, hydrogen peroxide vapours or reducing agents, tend to losetheir sensitivity and become spontaneously developable without anypreliminary exposure. This phenomenon is called chemical fog as todiiferentiate it from the light fog due to an undesired exposure. Thefog formation depends on the emulsion type and is directly proportionalto the age, the temperature and the relative humidity on storage.

It is also known that the silver image formed after exposure undergoes adegradation, by which is meant a shift and a decrease of intensity ofthe image tone during the finishing to a visible image e.g. under theinfluence of ingredients used in the developing bath, the fixing bath,

The greater part of these compounds, however, presents the draw-back ofbeing only active within well definite limits and of usually exerting astrong desensitizing action onto the emulsion.

It has now been found that the imidazolidine-4-thiones and theirtautomers corresponding to the following general formula wherein Each ofR R R and R (equal or different) represents a hydrogen atom, an alkylradical, a substituted alkyl radical, an alkaryl radical, a substitutedalkarylradical, an aryl radical or a substituted aryl radical; or

R and R and also R and R two by two represent the atoms necessary toclose a saturated homocyclic nucleus or a substituted saturatedhomocyclic nucleus,

are effective anti-bronzing agents and exert a stabilizing and afog-inhibiting action onto light-sensitive photographic emulsionswithout impairing their sensitivity.

Some compounds according to the present invention 3,148,538? PatentedSept. 15, 1964 Ice which appeared from the experiments to giveparticularly good results are identified hereinafter:

CO=S

I 2 CH These compounds may be prepared according to known methods ase.g. those described by l. D. Christian, J. Org. Chem, 22 (1957), 398;Bucherer and Brandt, I. prakt. Chem., (1934), 129; US. patentspecifications 2,785,175 and 2,806,036; C. A. 28, 4383 with reference toScience Repts., Tokyo Bunrika Daigaka, Sect. A. 2, 1-7 (1934), and C. A.22, 2146.

The preparation for the greater part corresponds with able layer such asa gelatin covering layer or to an intermediate layer adjacent to theemulsion layer. The used emulsions may be sensitized according to ausual process. They may be chemically sensitized by little quantities ofsulphurous compounds such as allyl isothiocyanate, allyl thiourea,sodium thiosulfate, etc. The emulsions may also be sensitized by meansof reducing agents e.g. the tin compounds described in the Belgianpatent specifications 493,464 and 568,687, the imino-aminomethanesulphinic acid compounds described in the Belgian patent specification547,323, and small quantities of noble metal compounds e.g. of gold,platinum, palladium, iridium, ruthenium and rhodium. The emulsion mayalso be sensitized by means of polyalkylene oxide derivatives e.g.polyethylene oxide, the molecular Weight of which varying between 1000and 20,000 condensation products of alkylene oxides with aliphaticalcohols or glycols, with cyclic dehydrated products of hexitols, withalkyl substituted phenols, with aliphatic carboxylic acids, withaliphatic amines and diamines, and with aliphatic amides. Thecondensation products may have a molecular weight of at least 700 andpreferably above 1000. v

In order to obtain well defined efiects, these sensitizers evidently maybe applied in combination, such as described e.g. in the Belgian patentspecification 537,278 and in the British patent specification 727,982.

Further these compounds may be applied in optically sensitized emulsionsas Well as in non-optically sensitized emulsions.

In order to obtain Well defined effects, these compounds may also beused in combination with other known stabilizers, e.g.7-hydroxy-S-alkyl-s-triazolo(2,3-a)pyrimidines e.g. in high-sensitiveemulsions containing a development activator of the polyoxyalkylenetype.

The compounds according to this invention may be applied to all kinds ofemulsions such as silver bromide emulsions containing a considerableamount of silver iodide, silver bromide emulsions, silver bromidecontaining silver chloride emulsions, and silver chloride emulsions,thus in all the usual negative and positive kinds of photographic filmsand papers. Especially in emulsions of photographic paper sorts whichafter development are submitted to high-glossing, the compoundsaccording to this invention are very efiicient as antibronzing-agents.

The quantity of stabilizers may vary according to the kind of the usedsilver halide or a mixture thereof, the degree of ripening, the presenceor the absence of other emulsion additives such as colour couplers,optical bleach- 7 ing agents, anti-oxidation agents, substancesinfluencing the image-tone, etc. Generally the quantity of stabilizervaries between 0.001 and 0.35 g. per mol of silver halide. In somecircumstances, however, e.g. in order to achieve determined effects,larger amounts may be used.

The following examples illustrate the invention, Without limiting,however, the scope thereof.

Example 1 To different samples of the same high-sensitive silverbromo-iodide emulsion (about 3.5% of iodide), amounts of stabilizers areadded as indicated in the following table. After chemical ripening theemulsion samples are coated onto strips of a support and dried.

After storing these light-sensitive materials in a warm and humidatmosphere they are exposed for 4 sec. and developed for 4 minutes in asolution of the following composition:

G. N-methyl-p-aminophenol hemisulphate 1.5 Hydroquinone 6 Sodiumsulphite 100 Sodium carbonate 80 Potassium bromide 2 Ethylenediaminetetracetic acid trisodium salt 1.5

Water to make 1 l.

After further treating this sensitive material in a stop bath, washingand fixing the following comparative results were noted.

Fog value Conoentra- Stabilizer tion in rug/mol of Of freshly After 36h. After 5 days silverhalide coated of ineubaof incubaemulsion Lion tion0. 09 0. 34 1. 22 Compound 1 6t] 0. 03 0.06 0. 20 Compound 1.. 0. 04 0.07 0. 20 Compound 2 30 O. 04 0. 10 0. 73 Oomoound 2 150 O. 03 0. 04 0.09 Compound 4 25 O. 05 0.13 O. 75 Compound 4 75 0. 02 0.03 0. 12Compound 5 30 0.04 0.09 I 0.47

These compounds are active not only as stabilizers or as anti-foggingagents, but they also improve the image tone of the developed image,especially in the case the photographic material is hot-glazed.Generally the image thus obtained possesses a bluish black tone withoutshowing, however, a metallic gloss.

Example 2 Example 3 By replacing in the emulsion of Example 2, 1.5 g. ofcompound 1 by 3.5 g. of compound 2 and treating as in that example, thesame results are obtained.

Example 4 To a silver chloro-bromide emulsion (35% of chloride) suitablefor enlarging negatives, 0.7 g. of the compound 3 is added per mol ofsilver halide. The emulsion is coated onto a paper support.

This material is exposed in an exact way and developed for 2 min. in asame solution as described in Example 1.

After further treating the material in a stop-bath, washing, fixing,washing and hot-glazing, a silver image is obtained possessing a bluishblack image tone without showingany metal gloss or bronzy decoloration.If the emulsion does not contain the above compound, the image tone ismore bronze-coloured and after hot-glazing, the silver shows a metallicgloss.

Example 5 By replacing in the emulsion of Example 4, 0.7 g. of compound3 by 2 g. of compound 1 and treating in the same way as in Example 2,identical results are obtained.

I claim:

1. Photographiclight-sensitive material comprising a 7 silver halideemulsion layer and containing in at least one of its water-permeablelayers an imidazolidine-4-thione of the formula:

R1 R1 t-e t-r HN NH HN N 5 6 wherein each of R R R and R is a memberselected of its water-permeable layers an imidazolidine-4-thione of fromthe group consisting of a hydrogen atom, an the formula alkyl group andan aryl group. R1 R1 2. Photographic light-sensitive material comprisinga R R 5 2 l silver halide emulsion layer and containing m at least one 5\L I ll of its water-permeable layers an imidazolidine-4-thione of HN NHthe formula: -Y Y wherein each of R and R is a member selected from thegroup consisting of a hydrogen atom, an alkyl group I T i HN NH HN N andan aryl group, and

Y represents the necessary atoms to close a saturated cycloaliphaticring.

19 References Cited in the file of this patent wherein each of X and Yare the necessary atoms to close Bruenner; Photographic S ien and Enineering, vol. 21 Saturat d cycloaliphati r g 4, No. 4, pages 186-495,July-August 1960.

Photographic light-Sensitive material Comprising a Futaki et al.:Photographic Science and Engineering,

silver halide emulsion layer and containing in at least one 20 vol. 4,No. 5, pages 257-263, September-October 1960.

1. PHOTOGRAPHIC LIGHT-SENSITIVE MATERIAL COMPRISING A SILVER HALIDEEMULSION LAYER AND CONTAINING IN AT LEAST ONE OF ITS WATER-PERMEABLELAYERS AN IMIDAZOLIDINE-4-THIONE OF THE FORMULA: